1. Field of the Invention
This invention relates generally to the field of window assemblies and specifically to an improved sash lock for limiting movement of a window sash.
2. Description of the Related Art
Double hung windows are one of the most popular types of windows for residential and other structures. A lower sash is usually disposed immediately inwardly of a upper sash so that the sashes overlap and slide parallel to each other in a window frame.
In order to limit relative movement of the sashes, a stop or limit device known as a "sash lock" has been used. Sash locks have many configurations, but typically include a tumbler pivotably disposed in a housing mounted in a stile of the upper sash. A spring urges the tumbler toward an extended position where the tumbler is engageable with the header rail of the lower sash to limit movement thereof. An upper rear surface of the tumbler engages a back wall of the housing to limit rotation of the tumbler. Examples of sash locks are shown in U.S. Pat. Nos. 417,868 to Janes; 614,741 to Moore, Jr.; 1,946,833 to Brown; 4,824,154 to Simpson; 4,923,230 to Simpson; and 5,248,174 to Matz.
Over-rotation of the tumbler has been a problem with sash locks. In some circumstances, the lower sash or the user may engage the tumbler in such a way that it does not properly engage the back wall of the housing. Thus, the tumbler may over-rotate and cannot adequately limit movement of lower sash. The present invention seeks to solve this problem and others in a simple, easily manufactured assembly.